Dash-pot.



PATENTED MAY 22, 1906.

S. P. WILBUR.

DASH POT. APPLICATION FILED APR.18,1905.

WITNESSES: @144. W m

rmrrnn STATES PATENT orrron.

I/VESTINGHOUSE ELECTRIC & PORATION OF PENNSYLVANIA.

MANUFACTURING COMPANY, A COR- DASH-POT.

Specification of Letters Patent.

Patented. May 22,1906.

Application filed April 18, 1905. Serial No. 256,274-

T0 at whom it may concern.-

Be it known that I, SAMUEL P. WILBUR, a citizen of the United States, and a resident of "Wilkinsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Dash-Pots, of which the following is a specification.

My invention relates to dash-pots, and particularly to dash-pots that are adapted for use in connection with arc-lamps; and it has for its object to provide a dash-pot that shall be simple in construction and effective in operation and shall also be self-lubricating and unaffected by variations in temperature.

Dash-pots for use in arc-lamps have heretofore generally been provided with graphite plungers ,which were selflubricating, but were hygroscopic to such degree when cooled after being subjected to the heat of the are that the low temperatures to which they were often subjected would effect such expansion as to seriously interfere with their operation. This disadvantage is avoided by my invention, which reduces the mass of the plunger by making it of tubular form. Although my invention does not modify the hygroscopic quality of the material, it reduces the mass, and consequently reduces the amount of moisture which can be retained therein, so that wide variations in temperature have no appreciable effect.

The dash-pot of my invention is not restricted to arc-lamp service and may be used for any convenient purpose; but it is specially applicable to service where relatively wide variations in temperature. are encountered.

My invention is illustrated in the single figure of the accompanying drawing, which is a sectional elevation of a dash-pot constructed in accordance therewith.

Referring to the drawing, a dash-pot 1 comprises a hollow metal cylinder 2 and a piston or plunger 3, which fits closely in said cylinder. One end of the cylinder 2 is c osed by a cap 4, that is provided with a small hole 5, which connects the space between the end of the plunger 3 and the cap 4 with the eX- ternal air, and a ball-valve 6, that serves to restrict the flow of air through the hole when the piston 3 is moved within its cylinder. The cap 4 is provided with a projection 7, by means of which the cylinder of the dash-pot may be connected to any desired mechanism. The piston 3 comprises a tubular body portion 8, composed of graphite or similar material having lubricating properties and having beveled edges, end plates or washers 9 and 10, having flanged edges to engage the beveled edges of the body 8, and a screw 11, that projects through the parts 8, 9, and 10 and into the end of a piston-rod 12 and serves to clamp the said parts together and to the end of the rod.

The ball-valve 6 is raised by the air-pressure when the piston 3 is moved toward the cap 4, but is drawn to its seat in the opening when the piston moves in the other direction, so that a partial vacuum is formed in the space between the piston and the cap when the piston is moved in one direction, and the air is compressed therein as the piston is moved in the other direction, so that its motion is retarded in each direction in the usual manner.

I claim as my invention 1. In a dash-pot, the combination with a cylinder that is open at one end and the other end of which is provided with a cap having a valved opening, of a piston and a connecting-rod attached thereto, said piston comprising a tubular body of lubricating material, end plates, and a screw that clamps the tubular body and end plates together and to the end of the piston-rod and is of materially less diameter than the interior of the tubular body.

2. In a dash-pot, the combination with a cylinder, of a piston comprising a tubular body of lubricating material, end plates or washers and a fastening-screw that clamps the tubular body between the end plates and is of materially less diameter than the interior of the tubular body.

3. In a dash-pot, the combination with a cylinder, of a piston comprising a tubular body of lubricating material having beveled edges, end plates or washers that are flanged to engage the beveled edges of said tubular body, a screw that passes through said washers, and a rod having an end socket to receive said screw. 1

4. The combination with a cylinder having a cap provided with a valved opening, of a piston comprising a tubular body of graphiteland end plates or washers therefor, a rod and a screw of materially less diameter than for clamping said tubular body and end 10 the interior of the tubular body for clamping plates together and to the end of the pistonthe piston parts together and to the end of rod.

said rod. In testimony whereof I have hereunto sub- 5. In a dash-pot, the combination with a scribed my name this 15th day of April, 1905.

cylinder, of a piston-rod and a piston com- S. P. WILBUR prising a tubular body of graphite, end plates Witnesses:

or Washers, and a screw of materially less di- OTTO S. SCHAIRER,

ameter than the interior of the tubular body BIRNEY HINES. 

